[squash] simply & rm one-off expectedError vars

test/parallel/test-child-process-fork-stdio-string-variant.js

@@ -13,10 +13,9 @@ const childScript = fixtures.path('child-process-spawn-node');
 const malFormedOpts = { stdio: '33' };
 const payload = { hello: 'world' };
 
-const expectedError =
-  common.expectsError({ code: 'ERR_INVALID_OPT_VALUE', type: TypeError });
-
-assert.throws(() => fork(childScript, malFormedOpts), expectedError);
+common.expectsError(
+  () => fork(childScript, malFormedOpts),
+  { code: 'ERR_INVALID_OPT_VALUE', type: TypeError });
 
 function test(stringVariant) {
   const child = fork(childScript, { stdio: stringVariant });

test/parallel/test-child-process-fork-stdio.js

@@ -19,12 +19,9 @@ if (process.argv[2] === 'child') {
     process.send(data);
   });
 } else {
-  const expectedError =
-    common.expectsError({ code: 'ERR_INVALID_OPT_VALUE', type: TypeError });
-
-  assert.throws(() => {
-    cp.fork(__filename, { stdio: ['pipe', 'pipe', 'pipe', 'pipe'] });
-  }, expectedError);
+  common.expectsError(
+    () => cp.fork(__filename, { stdio: ['pipe', 'pipe', 'pipe', 'pipe'] }),
+    { code: 'ERR_INVALID_OPT_VALUE', type: TypeError });
 
   let ipc = '';
   let stderr = '';

test/parallel/test-child-process-spawnsync-input.js

@@ -76,13 +76,9 @@ let options = {
   input: 1234
 };
 
-const expectedError =
-  common.expectsError({ code: 'ERR_INVALID_ARG_TYPE', type: TypeError }, 1);
-
-assert.throws(function() {
-  spawnSync('cat', [], options);
-}, expectedError);
-
+common.expectsError(
+  () => spawnSync('cat', [], options),
+  { code: 'ERR_INVALID_ARG_TYPE', type: TypeError }, 1);
 
 options = {
   input: 'hello world'